The objective of this program is to design, fabricate, optimize and use-test a dental x-ray aiming device. Beam alignment will allow the x-ray radiation to be collimated to the appropriate film size--thus substantially reducing spurious radiation. The aiming is accomplished via a permanent magnet attached to the film and a series of Hall effect probes located on the x-ray cone. The alignment system measures displacements along both the vertical and horizontal axis and angular rotations in three directions. The five-degree-of-freedom alignment insures that the beam and target lie on the same axis and that the target, i.e., film, is orthogonal to the incident beam. The alignment protocol is based on a series of vector relationships which are implemented on a micro-processor. The micro-processor is in turn coupled to a visual display which guides the operator in the alignment process. Further development and optimization of the alignment algorithms and training of operators will be carried out in the proposed program.